Cigarette smoking disorders the biology of the airway epithelium, often resulting in chronic obstructive pulmonary disease and/or lung cancer. Current studies in our laboratory, supported by R01 HL107882, focus on understanding how this disordered biology links to the increased risk of lung cancer in cigarette smokers with COPD. In response to PAR-12-010, we propose to expand these studies to include assessment of airway epithelium of smokers of shisha and electronic cigarettes to understand the extent, if any, to which these alternate nicotine delivery systems disorder airway biology. We hypothesize that shisha smoking and electronic cigarettes both disorder airway biology, but this disordered biology differs from that resulting from cigarette smoking, suggesting that these alternative nicotine delivery methods will cause lung disease, but perhaps with phenotypes different from that of cigarette smoking. Based on our data on the disordered airway biology associated with cigarette smoking (transcriptome, DNA methylation, telomere length, cilia length), and preliminary data with shisha smoking, the proposed studies will provide a comprehensive molecular catalog of changes in the airway epithelium associated with shisha and electronic cigarette smoking, providing insight that will guide public health education and regulatory measures related to these alternative nicotine delivery approaches. The focus will be on the small airway epithelium (SAE), the primary site of pathology in smoking-induced lung disease. We propose to assess SAE biologic parameters in 2 aims, one focused on shisha and the other on electronic cigarettes. Aim 1. To assess the hypothesis that shisha smoking disorders the biology of the airway epithelium, but that these changes are distinct from that of cigarette smokers. Using SAE obtained from pure shisha smokers (i.e., non-cigarette smokers) that are clinically healthy, we will assess SAE gene expression, DNA methylation, telomere length and cilia length compared to the same parame- ters in otherwise matched non-smokers and chronic cigarette smokers. Aim 2. To evaluate the hy- pothesis that when the smoker switches from smoking cigarettes to smoking electronic ciga- rettes, there is a partial normalization of the disordered airway epithelial biology, but that this partial normalization is different from that associated from complete cessation of cigarette smoking. Using the same parameters as in aim 1, we will assess what happens to the disordered airway epithelial biology when cigarette smokers switch to electronic cigarettes compared to cigarette smokers that stop smoking. This will be compared to the same parameters in matched nonsmokers and chronic cigarette smokers. PUBLIC HEALTH RELEVANCE: Cigarette smoking evokes major changes in the biology of the airway epithelium, the cell population that takes the brunt of the stress of cigarette smoke and the cell population central to the pathogenesis of COPD and lung cancer. The focus of this study is to identify the differences that two popular alternative nicotine delivery strategies, shisha and electronic cigarettes, have on the airway epithelium compared to cigarette smoking. We hypothesize that both alternative nicotine delivery strategies disorder airway epithelial biology, but in different ways than does cigarette smoking.